1. Field of the Invention
Generally, the field of the present invention is optical fibers. More particularly, the present invention relates to large mode area optical fibers and single-mode operation thereof.
2. Background
It is of increasing importance for industry to keep pace with the progress of small-scale technology. With the ability to process a variety of materials and at small-scales, laser systems are well suited for precision processing applications in corresponding technologies. In particular, high power fiber lasers are well-suited for such precision applications due to their compactness, efficiency, cost-effectiveness, and potential for single-mode performance, among other advantages. However, to increase the power capabilities of such systems that utilize optical fiber, various roadblocks exist. For example, in some approaches, the power scaling of fiber lasers requires large mode area fiber to provide single-mode performance, even as the core size of such fibers increases to diameters outside practical single-mode ranges, such as approximately 25 μm or less. The onset of higher order modes tends to significantly deteriorate the beam quality of the output beam from the fiber, resulting in less than optimal performance and limiting output power scaling. Various approaches that have been developed to push the power barrier have met with mixed results, remain under development, or are very expensive. Accordingly, there remains a need for fiber laser systems capable of scaling to higher powers.